In a wideband code division multiple access (W-CDMA) system, a total received uplink power in a cell is controlled not to exceed a limited specific value that is expressed by a rise over thermal (RoT) (total interference to thermal noise ratio that is used to measure how much a cell is congested). This is to secure the communication quality of a terminal existing on a cell boundary, and transmission power of a terminal is an important factor to determine the degree of uplink interference that influences another terminal.
As a power control method based on a general signal to interference ratio (SIR), inner loop power control is provided. This is for a base station to command a terminal to increase or decrease a power using a transmit power control (TPC) command that is transmitted in the unit of time slot through comparison of an SIR measured mainly using a dedicated physical control channel (DPCCH) with a target SIR. A terminal receives the TPC command transmitted by the base station, and operates to increase or decrease the transmission power (mixedly used with power) of the terminal.
In this case, the target SIR is adjusted by outer loop power control, and this is affected by a block error rate (BLER) of a data channel. That is, if a positive acknowledgement (ACK) for the transmitted data is received, the base station decreases the target SIR, whereas if a negative acknowledgement (NACK) is received, the base station increases the target SIR. Since the target SIR as described above is updated only in a data transmission period (mixedly used with active period or active state), the last target SIR value of the previous data transmission period is maintained as it is in a data non-transmission period (mixedly used with inactive period or inactive state).